APPLICATION OF A SUITE OF 16S RIBOSOMAL-RNA-SPECIFIC OLIGONUCLEOTIDE PROBES DESIGNED TO INVESTIGATE BACTERIA OF THE PHYLUM CYTOPHAGA-FLAVOBACTER-BACTEROIDES IN THE NATURAL-ENVIRONMENT

We designed a panel of four 16S rRNA-targeted oligonucleotide probes s pecific for bacteria of the phylum cytophaga-flavobacter-bacteroides ( CFB). Probes CF319a and CF319b are targeted to members of the flavobac teria-cytophaga group and the genus Porphyromonas, whereas probe BAC30 3 has a target region characteristic for the genera Prevotella and Bac teroides within the bacteroides group. The probe FFE8b was developed f or species-specific hybridizations with Flavobacterium ferrugineum. Al l probes were designed by computer-assisted sequence analysis and comp ared to all currently accessible 16S and 23S rRNA sequences. The oligo nucleotides were further evaluated by whole-cell and non-radioactive d ot-blot hybridization against reference strains of the CFB phylum and other major lineages of Bacteria. The newly developed probes were used together with other higher-order probes to analyse the structure and community composition in complex environments. In activated sludge sam ples, members of the flavobacteria-cytophaga group were revealed by in situ hybridization as important constituents of sludge flocs and char acteristic colonizers of filamentous bacteria, By application of fluor escent probe BAC303, members of the genera Bacteroides and Prevotella could be visualized without prior cultivation as an important part of the human faecal microflora.